Warren Buffet and Jay-Z have an unlikely friendship over the last couple of years as the two partied at the re-opening of Jay-Z's 40/40 Club in Manhattan.

Billionaire investor Buffet and rapper Jay-Z may not seem to have much in common on the surface, but that two have been business partners for some time and have teamed up for charitable projects.

Jay-Z, 42, and Buffet, 81, appeared together on the cover of Forbes magazine in 2010 and both joined Steve Forbes at the first-ever Forbes 400 Summit, according to Forbes.com.

Jay-Z also visited Buffet in Omaha and the two hung out at one of Buffet's favorite diners. In 2011, Jay-Z and Buffet also teamed up to launch a financial literacy program for kids called, The Secret Millionaire's Club.

They launched the online animated series to teach children about good financial habits. It aired in October 2011 on the children's network, The Hub, according to Business Insider.

The plan will also hold nationwide business competitions for kids between ages 7 and 16.

Jay-Z and Buffet were spotted partying together at the re-opening of Jay-Z's 40/40 Club this week, according to the New York Post. Director Spike Lee and The Roots drummer Questlove were also at the re-opening event.

Buffet posed for pictures, throwing up Jay-Z's diamond sign, according to the Huffington Post. Buffet reportedly saw others at the event throwing up the sign and asked Jay-Z what it was. Jay-Z informed him and then showed him how to make the hand gesture.

Buffet appeared in several photos, sporting a youthful smile and seemed to be enjoying himself in the company of celebrities like Ashanti and Russell Simmons.

According to TMZ, Buffet wasn't on the original guest list, but asked Jay-Z if he could crash the event. Jay-Z said yes and even gave Buffet a tour of the nightclub, which he really enjoyed.

It was Jay-Z's first appearance since the birth of his first child, Blue Ivy Carter. Several guests congratulated him as he showed them what is speculated to be pictures of his newborn from his phone.